Potential matching electrical control system



Patented Dec. 27,. 1949 UNIT-ED STATES PATENT OFFICE POTENTIAL MATCHINGELECTRICAL CONTROL SYSTEM Gerald Deak'in, New York, N. Y., assignor toInternational Standard Electric Corporation, New York, N. Y., acorporation of Delaware Application July 7, 1945-, Serial No. 603,640

11 Claims. 1

' This invention relates to electrical control systems in which acontrolled device is actuated when a potential applied to the system ata control station is matched by a potential applied to the system at anoperating station. It is particularly applicable to automatic telephonesystems, but may be used in control systems and especially remotecontrol systems of various types, such as electric elevator control, guncontrol, calculating machines, telegraph, ticket and other automaticprinters and the like.

The two potentials, or potentials derived from them, are applied to anactuating device which acts on the controlled device when the potentialshave a determined or matched relationship. In systems of this type thematching of the control station potential at the operating station isadvantageously accomplished by a searching device which successivelyengages points of diiierent potential that may be above, below or thesame as the potential selected at the control station. With thisarrangement the relative polarity of the two potentials may be reversedas the searching device travels over said points.

A feature of the invention is the utilization, in a system of theindicated type, of an actuating device including an element that reactsdifferently when the relative polarity of two potentials applied to theelement is changed, in combination with means for reversing connectionsbetween the element and the sources of the two potentials when therelative polarity between the potentials changes, so that the samerelative polarity is maintained between the potentials actually appliedto the element, regardless of changes in polarity of the potentials attheir station sources. More specifically the invention includes the useof a vacuum tube as such element of the actuating system, the potentialsbeing applied to the tube to control the potential relationship betweenthe cathode and the control grid.

The tube is connected to actuate the controlled device such as a relaysystem when the required anode current is generated. Whenever thepotential of the control grid of the tube is above the cut-off value theanode current will flow; and a feature of the invention is the provisionof an automatic system that will maintain the control grid potentialbelow the value at which the generated anode current will operate theactuated device, regardless of whether the potential at the operatingstation is above or below that at the control station, except when thepotentials are matched. The potentials are considered to be matched whenthey either are the same or have 2 a potential difference of the properpolarity at which the required anode current will flow.

The invention isespecially advantageous when utilized in an automatictelecommunication system in which a register at the control station isprovided with a brush moved over a series of contact points maintainedat different potentials, .and a selector at the operating station isprovided with a brush moved over a similar series of contact points. Thepurpose is to halt the selector brush on a contact point whose potentialmatches that of the point on which the register brush has been stopped.If the appropriate point is idle during the first passage of theselector brush the latter will be halted as soon as it reaches suchpoint; but if the latter is busy its potential will be changed in amanner set forth in ,Deakin application hereinafter set forth, and theselector brush will continue to hunt.

Consequently this arrangement would ordinarily apply to the actuatingdevice potentials both above and below the potential of the pointselected at the register. However, since the invention includes the useof an actuating device in which the applied potentials maintain the samerelative polarity, an automatic potential control system is employedwhich reverses the connections between the potentials at the stationsand the actuating device whenever the relative polarity of suchpotentials is changed, thereby maintaining the same relative polaritybetween the potentials applied to the latter device.

This invention is a modification of the control circuits disclosed inthe copending application of Gerald Deakin, Serial No. 484,184, filedApril 23, 1943, and in the various applications and patents referred totherein; said application No. 484,184 having issued as Patent .No.2,380,950 on August 7, 1945.

Other features and advantages of the invention will appear from thefollowing description con- .sidered in connection with the accompanyingdrawin which is a diagram of as much of a control system as is necessaryfor a clear understanding of the present invention.

The drawing illustrates the application of the invention to an automatictelephone system in which calling and called subscribers stations I and2 may be interconnected by means including a plurality of selectorswitches 3 and 4. The numerical operations of the selectors are controlled by the calling subscribers customary impulse sender, key senderor other common form of control device through the agency of a registerprovided at the central exchange. The calling station l is connected tothe brushes of selector 3 by Known switches (not shown) and a connectingcircuit 0, and the register is attached to the connectlng circuit :2through switching means 6.

The selector switches are of the customary type having a bank 01terminals with which a set of brushes cooperates. 1n the drawings threebrushes are snown i'or selector switch 3, the lowermost being designatedas '1, although the selector may have a larger number 01 brushes. Theselector brushes are moved over the selector terminals including testterminals ST while a magnet P is energized, and are stopped on a set ortermlnals when this magnet becomes deenergized, this cons tructlon andoperation being well known. The register comprises a series of switchessuccessively operable by the calling device in accordance withsuccessive digits of the called number which are dialed by the callingsubscriber. Brush BR and a set of terminals RT of one of these registerswitches are illustrated. This is the register switch which responds tothe digit in accordance with which the illustrated selector 3 is to beset. When brush RB is advanced toward one or its ten terminals inaccordance with the operation oi the calling device at station I, therelay ARI having been energized in the customary manner, a circuit isclosed from ground over the back armature and its front contact of relayARI, the armature and back contact of register relay VR, the Winding ofa ground relay GR, the winding of selector relay AR and the magnet P togrounded battery. A circuit is thereby closed from the battery throughmagnet P, relay AR, the armature and front contact of relay GR andresistor R5 to ground. Magnet P is energized and the brushes of selectorswitch 3 are driven over the selector terminals continuously in knownmanner until relay VB. is energized. The circuit of relay VR extendsfrom the anode oi tube V through the front contact and front armature ofrelay ARI to the positive terminal of the high tension battery HTB, thenegative of which is grounded.

Each of the register terminals RT is connected, preferably through asuitable resistor, to a source of potential, and in the illustratedarrangement these potentials are negative and increase progressively onsuccessive terminals by four volt intervals. The selector terminals STare similarly connected to corresponding negative potential sources. Itwill be understood that this particular potential arrangement, whileadvantageous, may be substantially varied within the scope .of theinvention. The brush RB is connected through the winding of gridtransfer relay GTR and rectifier S to the selector brush T. Brush RB isalso connected through the winding of cathode transfer relay CTR to saidrectifier.

The armature of the grid transfer relay GTR is connected to the controlgrid of the tube V and the armature of cathode transfer relay CTR isconnected to the cathode of said tube. The front contact of relay GTR isconnected to the back contact of relay CTR and to the selector brush T,while the front contact of relay CTR is connected to the back contact ofrelay GTR and to register brush RB.

With this arrangement current will flow through the relays GTR and CTRin parallel only when brush RB is positive with relation to brush T,since the rectifier S will prevent current flow through these relayswhen the brush T is more positive than brush RB. Consequently thecontrol grid of tube V will be connected to brush RB when this brush ismore negative, and to brush T when the latter is more negative and therelays and CTR are energized.

The characteristics or tube V are such that no cathode currentsuificient to energize relay VR will be generated when the control gridis negatively biased by the potential din'erence between the successiveterminals in the register and selector, but will flow when the potentialof the selected register terminal RT engaged by brush RE is the same asthat of the selector terminal ST engaged by the brush T.

In the operation of this system, which will appear from the foregoingdescription, the selector brushes will start hunting when the relay ARIis energized, closing the circuit through the drive magnet P including aseparate ground circuit, as well as the circuit through the magnetreleasing relay VR between the tube anode and the high tension batteryI-ITB. The selector brush T will apply varying potentials to theswitching relay system, which will apply such potentials to the cathodeof the tube V when they are more negative than the register brush RB,and to the control grid of the tube when they are more positive, thepotentials from the latter brush being correspondingly switched betweenthe control grid and the cathode, so that the tube is maintained belowcut-oli and does not generate anode current until brush T contacts aterminal having the same potential as the terminal engaged by brush RB.When this occurs the anode current generated by tube V energizes relayVR, cutting out the circuit through magnet and halting selector brush Ton the appropriate terminal. When relay ARI is deenergized, therebydeenergizing relay VR and closing the circuit through its armature tomagnet P, the latter circuit will be opened by the back armature ofrelay ARI so that the magnet P will remain inactive even though thecontacts of relay VR are closed.

It will be understood that the invention has been illustrated withoutcomplicating it by the If inclusion of other parts of the automatictelephone system in which it may be used, an embodiment of which isillustrated in the abovementioned Deakin application, Certain featureswhich might be added to adapt the illustrated arrangement to particularuses, to produce particular types of operation or to adapt the circuitto tubes having different characteristics have likewise been omitted,since the use of such features under appropriate conditions will beapparent to those skilled in the art.

Moreover, while the illustrated embodiment is especially adapted for usein automatic telephone systems, and in particular the relay systemactuated by the anode current of the tube is of a type suitable for usein such systems, it will be apparent that other types of controlleddevices may be actuated by the anode current.

Moreover, different arrangements for selecting and applying thepotentials to the two sides of 65 the switching system may be employed,though the disclosed arrangement has particular advantage when used withautomatic telephone systems including a selector and register, orcorresponding arrangements.

What is claimed is:

1. An electrical control system comprising actuating means responsive toa predetermined relationship in polarity and value between two appliedpotentials, means for providing a first 75 potential, means forproviding a second potential varying between values above and below thevalue of the first potential, means for applying said first and secondpotentials to the actuating means, and means for automaticallymechanically interchanging the applied potentials when the relativepolarity of the first and second potentials changes to maintain the samerelative polarity between the points of application of the potentials tothe actuating means.

2. A system as set forth in claim 1 in which the actuating meansincludes a vacuum tube and the potentials are applied to the electrodesof the tube.

3. A system as set forth in claim 1 in which at least one potentialproviding means includes a plurality of contacts maintained at differentpotentials and an operating contact successively engaging said contacts.

4. A system as set forth in claim 1 in which the interchanging meansincludes a relay in series with a rectifier which operates when therelative polarity of the first and second potentials changes.

5. .An electrical control system comprising actuating means including avacuum tube having a cathode, an anode and a control electrode, meansfor providing a first potential, means for providing a second potentialcapable of variation between values above and below the value of thefirst potential, means for applying to separate electrodes of the vacuumtube potentials corresponding to said first and second potentials, andmeans for automatically reversing the potential-applying connections tothe electrodes when the relative polarity of the first and secondpotentials is reversed, including a control circuit connecting thepotential providing means, a rectifier in the control circuit, and relaymeans in series with a rectifier in the control circuit, includingreversing switch means actuated by the relay means operating on currentflow in one direction only.

6. A system as set forth in claim 5 in which the relay means includestwo relays having windings connected in parallel, armatures connected tothe control grid and cathode respectively of the tube, each potentialproviding means being connected to the front contact of one relay andthe back contact of the other relay for reversing the connections of thegrid and cathode of the tube to the potential providing means when therelays are operated.

7. In a telecommunication system, a selector switch comprising aplurality of terminals connected to different potentials and anassociated brush and means for moving the brush over the terminals, aregister switch comprising a plurality of terminals connected todifferent potentials and an associated brush adapted to be set to aterminal representing a desired selection, means in the registerincluding a vacuum tube and relays for applying the potentials from thebrushes of the selector and register switches to different electrodesthereof, means for arresting the movement of the selector brush when thepotentials applied to the electrodes of the tube have a predeterminedrelationship, and means in the control circuit controlled by said relaysfor reversing the connections between the brushes and the tubeelectrodes when the relative polarity of the two brushes is reversed.

8. An arrangement as set forth in claim 7 in which the connectionreversing means includes a rectifier and relay means in series with therectifier for reversing the electrode connections between the brushesand the electrodes operated by a change in relative polarity of thebrushes, arranged to maintain the two electrodes at the same relativepolarity.

9. An arrangement as set forth in claim 7 in which the relay meansincludes two relays having windings connected in parallel, armatureseach connected to a different one of the electrodes, and front and backcontacts, each front contact being connected to the back contact of theother rela and to a different brush, arranged to provide a reversingswitch construction operative when the relays are energized and whenthey are deenergized to reverse the connections between the brushes andsaid electrodes.

10. Control means as set forth in claim 7, and means responsive to apolarity change for operating said relays for controlling the connectionreversing means.

11. Control means as set forth in claim 7, and uni-directional meansresponsive to a polarity change for operating said relays forcontrolling the connection reversing means.

GERALD DEAKIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,855,380 Breyfogel Apr. 26, 19321,903,837 Richardson Apr. 18, 1933 2,237,413 Clark Apr. 8, 19412,242,776 Clark May 20, 1941 2,245,160 Schimpf June 10, 1941 2,354,682Herbig Aug. 1, 1944 2,354,668 Deakin et al. Aug. 1, 1944 2,380,950Deakin Aug. 7, 1945 FOREIGN PATENTS Number Country Date 393,359 GreatBritain June 8, 1933

